For many years, decorative laminates have been used as a surfacing material in residential and commercial applications. Typical applications are surfacing for walls, partitions, table tops, counter tops, furniture, doors and the like. Decorative laminates of this type are usually produced by high pressure or low pressure methods depending upon the ultimate usage contemplated, the laminates produced utilizing high pressure techniques usually exhibiting superior properties.
High pressure decorative laminates are made of three essential layers: a core layer, a print layer, and an optional surface layer. The core layer constitutes a bottom or supporting layer onto which the other layers are bonded. In normal high-pressure laminate manufacture the core layer consists of a plurality of resin impregnated kraft paper sheets. Laminating resins commonly used include phenolic, amino, epoxy, polyester resins and the like. The industrially preferred laminating resin for decorative laminates is a phenolic resin. In low-pressure laminate manufacture, the core layer is generally comprised of a sheet of particleboard ranging from 3/8" to 1" in thickness.
Placed above the core layer is the print layer which is generally an alpha cellulose containing pigmented paper carrying a print, pattern, or design that has been impregnated with a melamine-formaldehyde resin.
The cured melamine-formaldehyde resins are colorless, resistant to light, solvents and stains and their heat resistance makes them immune to burning cigarettes, boiling water and heated containers up to about 325.degree. F.
The surface layer, or overlay, is a high-quality alpha cellulose containing paper impregnated with a melamine-formaldehyde resin. This layer is optional and protects the print sheet from external abuse such as abrasive wear and tear, harsh chemicals, burns, spills and the like. It is primarily the melamine-formaldehyde resin which accounts for these protective properties.
The core marterial, print layer and optional surface layer are stacked in a superimposed relationship, between stainless steel plates and subjected to a pressure and temperature for a time sufficiently long enough to cure the laminating resins impregnating the respective layers. The elevated temperatures and pressure actually cause the impregnated resins within the sheets to flow and thereby consolidate the layers into an integral mass.
For obvious economic reasons, it is common practice, when producing the paper supported laminates, to consolidate a plurality of these individual laminating assemblies into one large assembly, or press pack, said stacks being separated from one another by a release sheet, and then to laminate this pack by heat and pressure application.
In consolidating the laminate components according to most widely practiced techniques, an individual assembly is placed with its decorative overlayment surface adjacent to a highly polished stainless steel press plate. The function of the press plate is twofold. First, it provides a smooth, defect-free surface to one side of the laminate. Second, in connection with the paper based supported systems, it serves to separate pairs of back-to-back assemblies, thus permitting a plurality of these assemblies to be consolidated into laminates in one operation, usually in back-to-back relationship.
The heat and pressure consolidation of the laminate assemblies into useful laminates utilizing smooth, polished plates, results in the production of laminates having very glossy surfaces. When less glossy surfaces are required, an aluminum caul stock or a textured plate can be used to impart less glossy surfaces to the laminates.
As the decorative laminate art progressed, technicians continually strived to improve upon the aesthetics and properties of the high pressure and low pressure decorative laminates. One area where no significant developments have occurred is with regards to the mar-resistance of the laminate. Mar-resistance refers to the ability of the uppermost laminate surface to resist damage due to incidental or accidental contact thereof with an extraneous object. The propensity for laminate surfaces to exhibit poor mar-resistance is greater for laminates having high gloss surfaces than low gloss surfaces, especially where the decor sheet of the laminate is a solid color, and even more especially where the solid color is dark, e.g. navy blue, brown or black. Decorative laminates of this type show the "wear and tear" of everyday use more than laminates of a solid pastel color or laminates having a matte finish, regardless of which decorative pattern is employed.
Thus, there exists a need for increasing the mar-resistance of decorative laminates, the fulfillment of which would satisfy a long felt need in the art.